Patent Application
20090051608
1. Field of the Invention
The invention relates generally to an omnidirectional antenna and GPS antenna that is coupled with a protective mast.
2. Description of the Related Art
Radio antennas and antennas for receiving Global Positioning System (GPS) signals are a common site on both mobile (e.g., vehicles) and stationary objects (e.g., transmission towers). Sometimes, it is desirable to receive both radio and GPS transmissions at a single location or mobile object.
For a variety of reasons, the reception of both radio waves and GPS transmissions often are accomplished by using two separate antennas. Thus, for example, an automobile often will have both a standard “whip” antenna for radio wave reception and a separate “fin” antenna for GPS reception.
However, even single-unit, multi-frequency antennas are of limited use due to aerodynamic, space, and other considerations. Moreover, a difficulty in producing a combination GPS and radio antenna is that the electronics and mechanical structure for receiving the radio signal can interfere with the performance of the GPS antenna for receiving the GPS signal.
Many antennas are made wholly of wire and/or metal. However, this construction is unsuitable for applications in which the antenna is likely to be subjected to harsh conditions. For example, haul trucks at a mine site are used in rugged terrain and under conditions that tend to bend, corrode, break, an otherwise impair the function of an ordinary metal antenna. Furthermore, exposure of a metal antenna to extra-vehicular sources of electrical current (such as lightning or even overhead power lines in the case of large trucks) can present a safety issue.
Since it is desirable to have antennas at the highest point of an object in order to maximize reception, separate antennas for reception of radio and GPS signals often are placed at the highest part of a vehicle. However, this can lead to interference when both antennas are disposed at a similar height, and having two separate antennas can only increase the cost and time involved in maintaining and repairing antennas that become damaged.
The invention relates in general to an antenna that combines a GPS antenna, an omnidirectional antenna, and a protective mast. More particularly, the invention involves an omnidirectional antenna that is at least partially encased by a mast and includes a GPS antenna that is coupled with the same mast and is at least partially encased by a protective cover. The omnidirectional antenna is located above the GPS antenna when the mast is used in its normal vertical position.
Preferably, the cables connected to the omnidirectional antenna and the GPS antenna are housed within the mast so that they also are protected and isolated. Moreover, the mast most preferably is radio frequency (RF) transparent and made of low or non-electrically conductive material.
In one aspect of the invention, the mast is flexible and the mast and protective cover comprise a radome. In other words, the mast and protective cover enable the antennas of the invention to resist bending forces, impacts, ultraviolet light, and all types of inclement weather. Moreover, encasing the antennas of the invention provides a stronger overall structure, as the nesting of the antenna within the mast “reinforces” the mast.
The antennas of the invention are particularly useful in situations involving exposure to rugged conditions. Thus, for example, while exposure to sand, sun, rain, ice, dust, rock impacts, and tree braches would bend/deform, corrode, or break a typical metal antenna, the embodiments of the invention both maintain structural integrity and provide improved multi-reception functionality under harsh conditions.
Various other purposes and advantages of the invention will become clear from its description in the specification that follows. Therefore, to the accomplishment of the objectives described above, this invention includes the features hereinafter fully described in the detailed description of the preferred embodiments, and particularly pointed out in the claims. However, such description discloses only some of the various ways in which the invention may be practiced.
The invention relates to providing an omnidirectional antenna and GPS signal-reception antenna in conjunction with a single protective mast. The omnidirectional antenna and GPS antenna components are situated along the mast such that interference is minimized, yet both components can be positioned higher than the object to which they are attached for optimal reception.
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The receiver 36 is coupled to the mast 32 such that it is below the omnidirectional antenna when the mast is in a vertical position. This positioning of the antenna 36 and antenna 34 on the same mast has been found to lessen interference and yet provide for optimal reception capabilities. Preferably, antenna cable 42 and antenna cable 44 are disposed inside the mast 32, which is substantially non-conductive (i.e., little or no electrical conductivity).
Also preferably, the mast 32 and/or protective cover 38 is flexible and a radome. A radome is a structural, weatherproof enclosure used to protect an antenna. What distinguishes a radome structure from other structures is that the material used in building the radome allows a relatively unattenuated electromagnetic signal between the antenna inside the radome and outside equipment. In other words, RF transparency is characteristic of a radome. Using conventional whip antenna materials (i.e. steel, aluminum, etc.) would block most if not all of the antenna signal. Moreover, a radome protects the surfaces of the antenna from the effects of environmental exposure (i.e., wind, rain, sand, UV, ice, etc.). Fiberglass or an acetal resin engineering plastic, such at that sold under the DELRIN brand name, are examples of flexible radome materials.
Thus, the mast 82 is secured to vehicle 70 such that both the antenna 82 and the antenna 84 are higher than the vehicle 70 and overhang 74.
Various changes in the details and components that have been described may be made by those skilled in the art within the principles and scope of the invention herein described in the specification and defined in the appended claims. Therefore, while the present invention has been shown and described herein in what is believed to be the most practical and preferred embodiments, it is recognized that departures can be made therefrom within the scope of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent processes and products.
